Pulsation damper



May 2, v1944. H. GLUCK ET AL PULSA'IION DAMPER :s Sheeis-Sheet 1 FiledNov. 16, 1942 M y 2, 1944- H. GLUCK ET AL 2,347,903

PULSATION DAMPER Filed Nov. 16, 1942 3 Sheets-Sheet 2 F- IE.4.

BY: Z

EIR ATTOR Y.

y 1944. H. GLUCK ET AL 2,347,903

PULSATION DAMPER Filed Nov. 16, 1942 5 Sheets-Sheet 5 Fl -fi- PatentedMay 2, 1944 2,347,903 PULSATION DAMPER Harry Gluck, and Daniel J.Snyder, Edgewood, Pa.

Application November 16, 1942, Serial No. 465,788

' 2 Claims. (Cl. 138-40) This invention relates to pulsation dampers andmore particularly to such dampers that are used for preventingpulsations of a stack draft recorder.

In the gaging and recording of pressures, pulsation in pressure is oneof the mainsourcesof trouble. The rapid changes in pressure interferewith the proper recording and gaging of pressure and in some instancesthe change may be so great that the gage and/or recorder are corderchart obtained while using our pulsation damper. 1

Referring more particularly to the drawings, reference numeral Iindicates a stack draft recorder which is to be protected by ourpulsation I damper. This recorder is connected to the stack damagedthereby. When a recorder is usedit is not obtained.

To our knowledge, the only other instrument used for pulsation controlis a damper having spiral constricting tubes. If these become cloggedwith dirt, or are damaged in any way, the damper must be completelyreplaced. If it is desired to decrease or increase the dampening effect,another damper must be substituted.

It is an object of this invention to make a damper; which can be easilycleaned and which has a replaceable dampening unit.

Another object is'to obtain a clear recorder chart which can be easilyplanimetered.

Still another object is to provide for gage adjustment without breakingany of the pipe connections.

A further object is to provide a safety tap on the damper to protect thegage against sudden linesurges.

These and other objects will be apparent from the following descriptionand drawings in which Figure 1 is a layout of an installation of thepulsation damper;

Figure 2 is a cross-sectional view ofthe pul' sation damper;

Figure 3 is an end view of the removable cartridge;

Figure 4 is a reproduction of a draft gage recorder chart obtainedwithout using our pulsation damper; and

Figure 5 is 'a reproduction of a draft gage reby means of piping 2, thepulsation damper 3 and the piping 4. A needle valve 5 in the line I actsas a shut-oil! valve.

As best shown in Figure 2, the pulsation damper consists of a body 6having a threaded connection 'I for connection to the inlet piping 4 anda threaded connection 8 for connection to the outlet piping 2. The body8 is hollow and has a threaded connection 9 for receiving a removablecartridge III which supports a plurality of capillary tubes l I. Thiscartridge may be replaced by another cartridge having diflerentresistance to flow. If it is desired to use the same cartridge to obtaina different resistance, one or more of the tubes Il may be plugged. Agroove 12 in the cartridge enables it to be easily removed by means of ascrew driver. As the pressure in the line varies the pen of therecorderwill vibrate, giving a blurred effect as shown in Figure 4. Thepulsation damper by means of the restriction of flow in the capillarytube ll prevents the rapid fluctuation of the recorder pen l3. when itis desired to have greater restriction to flow, we may decrease thenumber of tubes or increase their length and/or 1 decrease theirdiameter. By varying these three factors any desired restriction-to flowmay be obtained.

.If the'fluid in the line is dirty, the tubes ll may be protectedby'inserting a strainer on the inlet side of the tubes. If the tubes Hbecome dirty, they may be cleaned by means of a wire. Such cleaning isnot possible when using a spiral pulsation damper.

In previous installations, if it were desired to calibrate theinstrument, it was necessary to break the connections in the line. Toovercome this, a pressure tight plug it is screw-threaded into the body6. This plug contains a threaded bore IE, to which a pet-cock I8 isconnected. Thegcalibrating instrument may be connected to the pet-cockand therefore it is not necessary to break any connection in the line.

To protect the instrument from damage on account of sudden surges inpressure, there is a tap I! in the body or the end opposite plug H. Tothis is connected a safety seal l8. In case the line impulse should goover the maximum recorder element pressure, the. safety connection forthe A safety pop-oi! valve or other safety device may be used in placeof the U tube.

While the invention has been disclosed as applied to a stack draftrecorder. it may be applied to any recorder or gage using a fluid mediumsuch as air, gas, oil, water. and steam, as long as the medium is nottoo viscous to ilow through the capillary tubes. The medium used willdetermine the kind of material to be used in constructing the pulsationdamper. Ordinarily the damper is made of non-corrodible material and thestrength is varied in accordance with the pressure to be gaged.

Briefly the operation the damper is as follows:

The needle valve 5 operates as a shut-off valve.

When pulsations occur, they are dampened as they are transmitted throughthe capillary tubes. thus increasing or decreasing the pressure on theinstrument side gradually instead of suddenly, until equal pressures areagain achieved. This allows the element in the recorder to oscillatecorrectly at each pressure change, rather than recording extremely highor low due to the pulsations. This achieves our purpose or obtainingreadable and accurate charts, which may be readily planimetered as isapparent from an inspection of the chart shown in Figure 5. This chartplainly shows the difference in checker resistanceof the open hearthfurnace and shows all furnace reversals. Advantages of the pulsationdamper are adjustment by means of the needle valve improves thereadings. but this requires constant attention and the readings are notas clear as those obtained when using the damper. In case the lineimpulse goes over the maximum recorder element pressure, the safetyconnection on the damper enables the line impulse to bleed directly tothe atmosphere. When it is desired to calibrate the instrument, it isonly necessary to close shut-oi! valve I, connect pet-cock II to thecalibrating instrument and open pet-cock ll. When cleaning or replacingthe removable cartridge ll, valve lis closed. the plug it is removed,and the cartridge unscrewed irom the body.

While a particular modification of our invention has been disclosed anddescribed. it will be apparent that we do not wish to be limited exactlythereto. since various modifications may be made while remaining withinthe scope of the following claims.

We claim:

1. A pulsation damper comprising an elongated hollow body open at oneend, an inlet at one end of the body connected to a source offluidpressure, an outlet at the other end oi. the body connected to apressure gage, a removable cartridge within the body located between theinlet and outlet, a plurality of capillary tubes extending lengthwise ofthe body and supported by the cartridge, and a plug for closing the openend of said body. said plug having a diameter of suiflcient size topermit removal of said cartridge from said body.

2. A pulsation damper as defined in claim 1 having a pressure releasedevice attached to the body between the inlet and removable cartridge.

HARRY GLUCK. DANIEL J. SNYDER.

